In recent living environments, convenience has been further improved by electronics, household electric appliances, in-vehicle devices, and the like which are equipped with a new function that is not found in the related art. As a background thereof, it can be said that sensor functions, which compensates the five senses of human beings, are a large portion. Increases in the number of these products have been significantly expected in a wide range of fields. Examples of a sensor include various sensors using a semiconductor, and various sensors including a pressure sensor, a flow rate sensor, a motion sensor, a luminance sensor, a distance measurement sensor, and the like have been made into products.
Among the sensors, an optical sensor including the luminance sensor has been frequently used, and has been spreading widely due to an increase in mounting on an illuminating device for an office or a house, a portable terminal, a computer, and the like for use accompanied with low power consumption. Products, on which the sensor component is mounted, have characteristics in which diversification of application, abundance of functions, and a design excellent in portability are favorable. In addition, a reduction in size, thickness, and cost, and high reliability are required in the products without exception. Among these requirements, a requirement for a package occupies a large portion. According to this, in development of the package, application of the related art or of new technologies has become increasingly important.
FIG. 7 is an example of a cross-sectional view of a packaged optical sensor. An optical sensor element 24 is mounted on an insulating substrate 22 on which an interconnection pattern 21 is formed through metallization, and a light-transmitting epoxy resin 29 is molded at the periphery of the optical sensor element 24 (FIG. 2 of Patent Document 1). In the package, the periphery of the optical sensor element is molded with the light-transmitting epoxy resin, and a resin 23, which uses a composition of blocking an infrared light beam, is provided in a layer shape to overlap a flat surface of an outer surface of the light-transmitting epoxy resin in a layer shape in an immediate upward direction of the optical sensor element.
As the optical sensor element 24 that is mounted, a light-receiving sensor element is used. The interconnection pattern 21, which is obtained through metallization, is electrically connected to an electrode provided on an upper surface of the optical sensor element 24 through a wire 25, and is used as a connection terminal with an outer side. An electromotive force, which is generated by a light beam that is incident to the light-receiving sensor element, is transmitted to an external connection terminal through the wire 25. Light beams, which are incident from an outer side in an immediate upward direction of the optical sensor element, are transmitted through the light-transmitting epoxy resin after an infrared light beam is blocked by the resin 23, and thus the optical sensor element is sensitive to light beams in a manner close to spectral luminous efficacy properties specific to human beings.
However, in the package structure described in Patent Document 1, the resin having a composition of blocking an infrared light beam is provided on the outer surface of the light-transmitting resin that molds the periphery of the element only in the immediate upward direction of the element. Therefore, with respect to light beams which are incident from an oblique direction, or light beams which are incident from a lateral direction, it is difficult to block the infrared light beam, and it is difficult for the element to receive light beams having characteristics on which the spectral luminous efficacy properties are reflected. According to this, it is difficult to obtain sufficient spectral luminous efficacy properties with respect to light beams which are incident from the lateral direction or the oblique direction. As a result, it is difficult to obtain high light reception characteristics.
In addition, the package has a structure in which the periphery of the element is molded only with the light-transmitting transparent epoxy resin. It is known that the light-transmitting transparent epoxy resin is weak to heat and moisture. When discoloration of the resin occurs due to heat, the transmittance decreases. Therefore, light beams incident from an outer side are attenuated. As a result, an intensity of the light received by the optical sensor element decreases, and this decrease leads to deterioration in light reception sensitivity. In addition, the resin becomes brittle due to heat and peeling-off or cracking is likely to occur between the resin and the element. In addition, light beams incident from an outer side are attenuated, and this leads to a decrease in the optical intensity of the element, and a deterioration in the light reception sensitivity.
In addition, the light-transmitting transparent epoxy resin is likely to swell due to the effect of moisture, and the strength of the swelled resin is likely to decrease, Accordingly, there is a concern of the molded resin being deformed or broken due to impact from an outer side. In addition, the adhesiveness of the resin is likely to decrease due to an effect of moisture, and the moisture is likely to intrude from an interface between the resin and the element. In a case where moisture is interposed between adhesive surfaces of the resin and the element, the adhesiveness of the resin significantly decreases, and this leads to occurrence of interface peeling-off between the element and the resin. In addition, when heat is applied, moisture rapidly evaporates. Accordingly, a popcorn phenomenon occurs, and is accompanied with occurrence of cracking of the resin in addition to spreading of the interface peeling-off Therefore, light beams incident from an outer side are attenuated, and the attenuation leads to a decrease in optical intensity to the element, and partial breakage of the mold resin. As a result, it is difficult to obtain high reliability.
In addition, the resin which is provided on an outer surfaced of the light-transmitting transparent mold resin to block an infrared light beam is also a resin-based dye. Accordingly, there is a concern that a decrease in characteristics of the resin is also likely to occur due to heat or moisture. Particularly, in a case of the resin provided with specific properties of blocking an infrared light beams due to a composition or a structure of the resin, it is typically pointed out that characteristics tend to be unstable due to occurrence of leakage of the dye with respect to external factors such as heat and moisture. When both of the light-transmitting transparent resin that molds the periphery of the element, and the resin that blocks an infrared light beam deteriorate, a plurality of resin factors, which have an effect on the reliability, exist. As a result, it is difficult to obtain high reliability.
In addition, when miniaturization and thinning of the package are performed, the thickness of the mold resin further decreases. According to this, the peeling-off of the resin, the cracking, the discoloration, and the like are further likely to occur, and a decrease in mechanical strength or easiness of deformation also occurs. As a result, the reliability of the package is further likely to deteriorate.
A method of obtaining spectral luminous efficacy properties by using a material other than the resin, or a package having a hollow structure in which the periphery of the element is not molded with the resin have been partially put into practical use. In a case of the method of obtaining the spectral luminous efficacy properties by using a material having a reliability higher than that of the resin-based dye, a variation in the spectral luminous efficacy properties and a decrease in light reception sensitivity of the element due to resin factors, such as deterioration, peeling-off, and cracking of the resin, disappear. As a result, the stability of the characteristics over a long period of time is realized. In addition, when employing the hollow structure in which molding of the periphery of the element with the resin is not performed, the element does not receive a stress due to the resin. Accordingly, it is possible to remove a factor which greatly damages a function relating to a product, such as stress damage on the element and wire disconnection. As a result, it is possible to realize a package with high reliability.